Analysis of a twin pregnancy with false negative result for 22q11.2 deletion syndrome by expanded non-invasive prenatal testing.
10.3760/cma.j.cn511374-20210628-00551
- Author:
Ganye ZHAO
1
;
Zhihui JIAO
;
Peng DAI
;
Xiaoyan ZHAO
;
Xiangdong KONG
Author Information
1. Genetics and Prenatal Diagnosis Center, Department of Obstetrics and Gynecology, the First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan 450052, China. kongxdgene@163.com.
- Publication Type:Journal Article
- MeSH:
Pregnancy;
Female;
Humans;
Prenatal Diagnosis;
Pregnancy, Twin/genetics*;
DiGeorge Syndrome/genetics*;
DNA Copy Number Variations;
Amniocentesis
- From:
Chinese Journal of Medical Genetics
2023;40(12):1451-1454
- CountryChina
- Language:Chinese
-
Abstract:
OBJECTIVE:To explore the cause for a twin pregnancy with false negative result for 22q11.2 deletion syndrome by expanded non-invasive prenatal testing (NIPT-plus).
METHODS:A pregnant woman with twin pregnancy through in-vitro fertilization and negative result of NIPT-plus was selected as the study subject. Amniocentesis was conducted after ultrasonic finding of fetal abnormalities. In addition to conventional G-banded karyotyping, copy number variation sequencing (CNV-Seq) was used to detect chromosomal microdeletion and microduplication. Clinical data of the woman were analyzed to explore the reasons underlying the false negative result.
RESULTS:NIPT-plus has yielded a negative result with 11.77 Mb unique reads and 3.05% fetal fraction. Both fetuses had a normal karyotype (46,XY and 46,XX). CNV-seq indicated that one of the fetuses was normal, whilst the other was diagnosed with a 2.58 Mb deletion in the 22q11.2 region.
CONCLUSION:The false negative result may be attributed to the combined influence of low fetal fraction, high BMI, twin pregnancy through IVF and a relatively small deletion fragment. Ultrasonography exam following a low-risk result of NIPT-plus should not be neglected.
